First of all, I hate perforce.

Streams are essentially branches. Double click on a stream icon to work in that stream. The stream you're in has a little monitor icon next to its name. E.g. in the below i am in main.

In perfoce this is called submitting. Just go into the pending tab, right click on the red changelog, and click submit

Just click the refresh button, then click the projects root folder (VIP... not the directory path above it) and click "Get Latest"

Mering is a bit more complicated than in git. Perforce convention in "merge down copy up". So if you want to achive parity between main and a child stream you must do the following.

1. Right click on the stream you want to merge with main and select Merge / integrate ....

2. Click Merge

3. Go to your pending tab (this is like the changelog) and click resolve

4. Pick your resolve option

5. Click Submit (essentially the same as commit)

6. Right click on the Main stream and select "Copy files"

7. Resolve and submit in main just like before