Clear temporary files?

I'm also fairly new to OSX so I'm no expert, but I think that OSX does the "disk cleanup" and "disk defrag" automatically when needed

 

mdickson is right.

If you sleep your machine as opposed to shut it down each night, then OSX will also handle all the periodical maintenance tasks for you such as clearing out temporary files and logs. OSX also defrags files under 25MB (or 20MB, I always forget) as you go.

 

Scratch File

I am relatively new to using a MAC. This past week I was working with some very large files. Last night, I went to convert a typical image to a lower resolution image so I could put it on a website, and my photoshop wouldn't save it. I got an error message that my scratch file was full. I did some checking, but can't figure out how to delete or change my scratch file so photoshop will work again. Anybody have any suggestions for me? I need to get this website I'm working on done today, but can't figure out how to get photoshop back up and running. Thanks.