downloading files, newbie questions

Long time PC user, new to Mac.

Trying to download free fonts off the internet.
Question: After the file downloads to my "Download" folder what do I do? I double click on the file but get a message saying the file can't be opened. Am I doing something wrong?

Thanks.

are they TTF fonts?

Font Book should open up and give you the option to install

But if you plan on loading up loads of fonts, font book is not your best font manager

Take a look at Linotype FontExplorer - a professional level manager that is free (its kinda like Itunes for fonts, and will manage a large font library with ease)

Thanks, louishen.

I don't know what TTF fonts are.

Is there a way to get my downloaded fonts to show up in my applications...i.e. Keynotes when I click on the fonts menu?

When using a program like Linotype FontExplorer, what is the process for using the fonts found there in my applications (again, Keynotes).

Sorry if these are obvious questions but I'm new to this stuff.

Right click the file you downloaded and click "Get Info" - there should be a box under "Name & Extension" - copy and paste what is in that box.
That will tell us the file type which will allow us to explain how to install or why it's not working

Okay. Here's one I downloaded but that's as far as I can get with it.

acharmingfont.sit

A lot of fonts I want to download have the .sit extention. Will I be able to use these?

.sit = Stuffit compressed file. Download the free Stuffit Expander from Macupdate.com.
Or use The Unarchiver. sit is getting out of date as most people are using .zip which is native in OS X.

Now we're getting somewhere.

The Stuffit Expander worked as far as downloading and being able to open the .sit file. Now, how do I get that downloaded font file to work with Keynote and other programs?

All help is appreciated.

Try putting them in (your home folder)/Library/Fonts