To post to the activity feed, select the desired project from the main dashboard and click on its name. 

After opening the respective page, locate and click on the "+" button situated at the bottom of the page.

To choose the desired pictures from your camera roll, simply click on them. Alternatively, you can capture a new photo by clicking here and utilizing the camera:

If you want to use your camera for taking new photos, note that you can take multiple photos at once, the counting will show the number of pictures:

Preview them:

Once you have made your selections, you will be able to view the chosen items. If you wish to deselect certain items, you can do so by clicking on the bin icon located here:

To add tags and phases to your post, click on the "Add Tag" button at the bottom of the page. You can select phases and scheduled items by clicking on the "+" sign and remove them by clicking on the bin icon:

For choosing post visibility, click here:

Select who can see your post:

To select specific members, go to the list and choose the "specific members" option. From there, you can either select from the pre-existing options or click on "Create Custom Audience" to create a new one.

To choose members, simply type their names and provide a name for the audience in the "Group Name" field.

Click on "Add File" for adding files to your post:

Choose the files from your phone storage:

Your post can also include message part. Simply click on messages and type your message:

Text will appear like this:

If you want to discard the post, click on the "X" icon on the left bottom of the page:

Please note that in order to make a post, it is necessary for your post to include either a picture, file, or text.