Regarding document creation and saving in my mobile.

First of all, you have to install Google Docs app on your mobile. It will be available on Play store on all android phones.
Once you install that, click on that app to open. You will find a list of documents on your mobile. In some mobile on this page on the right-hand side corner in the bottom, you will find + or in some, you will see create. Click on that Then you can click on the option new document. A new page will open. You can type there your document.
This is how you can create your new document.
After typing, click on the three dots appear on the right side top corner. A list will dropdown. Click on share & create. Again a new list will come. in that list, you will find 'Save As'. Then the phone will ask the format. You can select the format you want. Then click on that format. the file will be saved in the docx l file.
This is how we can create and save a file on our mobile.

Earlier we were using mainly desktop computers for creating a document but now mobiles are also equipped with document making softwares or applications so making a document in mobile is now a easy process. There are many applications available in Play Store which can be used for document creation and saving in the mobile. Some of these are free while others are available for a price or monthly rentals. One can comfortably create documents using these apps and save them in one's mobile device. Some of these Apps are as follows -
1. AndrOpen Office.
2. Documents To Go.
3. Kingsoft Office.
4. QuickOffice.
5. OfficeSuit.
6. Quip.
7. SmartOffice.
8. WPS Office and PDF.
9. Polaris Office.
10. ThinkFree.
11. Picsel Smart Office.
12. Google Docs.

You may have the Galaxy Store as well as Google play store in your device. If you open either of them and search for
MS office, Word (relevant search word) etc you may get a number of free apps in that category listed.
For getting Galaxy store you may have to click on Samsung icon.
From the list you can select the one appropriate for you considering your requirement, app storage space, etc. But before installing please go through the descriptions and reviews given by other users. The more number installed, the more number of high star ratings, the more number of good reviews will be an indicator for its popularity and utility.
Then install following the installation guidelines. Open the app and start using it after familiarising it.
For creating a new document you have to open the relevant app and opening new document you can start creating the document. To store in your SD card give storage option as SD card.
After a few occasions you will become quite familiar and will be comfortable as you are with your computer now.

Earlier when we were using Desktop and Laptop we used to create documents in MS Word, Adobe PDF creator. Now we can see that for a four-member family all of them are having mobile phones on their own. For creating files on the mobile can use either Adobe Scan or Microsoft lens. Nitro PDF can also be used for creating the documents. When we edit the files on the mobile, we can save it as PDF file type, so we will get documents as PDF format. Even if we are using word document we can convert files into PDF format by using converting software.

Creating a document in Android is done with downloading those required apps only. Among many of the Document apps, the best is Microsoft word app. You can easily download Microsoft Word on your mobile phone which is available on the play store, that works the same as you are using on your computer.

You can not be required to download or purchase MS office in your mobile and Microsoft Word app is absolutely free for Android, after sign in with a Microsoft account.

Microsoft word requirements:
1. Support for Kitkat and Lollipop devices.
2. Requires Android version 6.0 and up.

You are using Samsung Galaxy J2 mobile is a Lollipop supported device, and you have to check whether your Android version is 6.0 or above, before download.

Microsoft Word facilities:
1. The app lets you create, read, edit, and share your files quickly and easily. You can create a new document by simply clicking the "+" button and choose Document style. You can find documents listed to read, edit, and share.
2. You can save the document as a word file or you can convert the word file into pdf file easily by clicking three dots on the top right corner and click "share as pdf" to save where you want to save either sd card or in your mobile storage.
3. Here you can have the advanced option to dictate, like voice typing available in the latest version of Microsoft Word.

If your Android version is below 6.0, you cannot use Microsoft Word on your mobile.

For that, you can use Google Docs.

It requires Android 5.0 and above, and the app is perfectly suited for your mobile to use.

Google Docs facilities:
1) You can create, view, and edit Google documents, as well as Microsoft Word files, with the Google Docs app.
2) You can create a new document by clicking File -> New.
3) You can also convert the document into Pdf file easily by clicking File -> Download -> PDF Document.

But in many areas, Microsoft Word comes out just ahead of, when compared to Google Docs. If you need the extra functionality.