Not really sure what the double arrow is myself..but If you select the mask in your composition panel you should get a box around it in your preview. Shift+Click on any of the 4 corners to scale proportionally. Click only to scale freely.
Sorry to everybody for such a delayed response. I do appreciate it. Just got really busy.
I did finally manage to realize that you have to click on the vertices to get the free transform tool to appear.
I earlier went to Adobe before CC. Adobe's instructions are difficult to translate half the time. I also don't read very well. I really try, but this didn't work for me:
"To transform an entire mask or shape path, select it (it?) in the Timeline panel and choose Layer > Mask And Shape Path > Free Transform Points."
Well, I tried the menu and layer and the Free Transform Tool was shaded out.
Some things are just easier to learn in AE by video I guess. I still can't get the double-arrows to come up. I did once then lost it. Thank goodness somebody on Adobe TV did a demo. I'll have to check it out.
Thanks so much Dave and and everybody else for chiming to help me out. It is appreciated.