I use Tapatalk on a mobile phone and tablet. Both are Android devices, sorry I don't have access to any Apple products running Tapatalk. The process for attaching and uploading pictures should be similar but if anyone is using an iPhone or iPad and is successfully attaching images to the forum please PM me if the instructions should be different.
Open Tapatalk and create a new post. In the upper right corner touch the menu icon (3 vertical dots). Select Attach Picture...
On the tablet I get to choose from the photo gallery or I could take a photo with the camera.
Select your image or take a new one. Once done you should be back at the new post with an attachment like this...
Touch Submit and you are done.
If you wanted to upload multiple photos just repeat the option of selecting pictures.