You'll need to ensure your GIF files are looped prior to uploading them to your Behance project. To do this, you can use Photoshop or an external image editing software such as LunaPic.

If you are using Photoshop:

1. Open your file in Photoshop
2. Go to File and click Save For Web
3. At the very bottom of the save dialog, you will see the Animation section, which should no longer be greyed out
4. Choose how you want it to loop and then preview the animation before saving it

If you are using LunaPic:

1. Go to the LunaPic site
2. Click Browse to upload the GIF from your computer, or enter the URL next to Open From URL and click Go
3. Click Animation from the menu at the top
4. Click Edit GIF Animation
5. Click the drop-down menu next to Looping and choose how many times you want the GIF to loop
6. Click Apply