need help with scripting, can select client

hey everyone,
For the last few days Ive been watching a alot of videos and reading guides. Tonight i downloaded simba after a bit of a problem of having a mac.
Now when i try and select the client(runescape screen) i cant highligh it(turn it red) as soon as i get off the simba page the hole screen trys red. If I select the hole screen i can do a few things, like getting the x, y to get it to click but when i went to try and make a DTM i just get a white screen no matter what i have selected.

any help would be great i was really looking forward to learning how to do a few things