How to upload code in github using github GUI?

Step 1:

At first go to your repository.
Then click on add file option(yellow marked in the image).

After clicking you will see two options:
1. Create new file
If you want to create any type of file using github GUI then click on this option. After creating file you can also write inside that file using github GUI.

2. Upload file
To upload files click on this option.

Step 2:

Now click on yellow marked area. After clicking you will be able to select files and folders from your desktop. So select all files and folders which you want to upload.

Now in the blue marked area write commit message.

In the brown marked area write some description.

Now you want to upload the files in main branch then select the green marked area or if you want to create a new branch and there if you upload the files then select red marked area.

If you select red marked area then you will see a new option, there you have to put your branch name.

Now click on commit change(orange marked area) to upload the files.