I like this girl that i went to high school with and now i work with her. i think she likes me but im not sure, and i want to ask her out but im not sure how to do it and not look like a joke

Since you are apparently not 12 years old, I don't see why this is such a challenge. Just ask her if she will have dinner with you Friday night. What's hard about that?

give her you secret smile and drop a few sompliments see how she responds to that dude i sympathise im one of those self confident lackin guys who very rarely has the confidence to ask girls out

2nd Answer:

If she says those three killer words, "i'm seeing somone", then you have my permission to say a cuss word.

It helps.

You're thinking too much. If you think she likes you then you must talk regularly. Ask if she'd like to go to dinner after work sometime - keep it casual. If she says yes then say something like "well, what day is best for you." I also strongly suggest flirting w/ her for a while before asking her out.

"Hey, would you like to go out for coffee or a bite next week? Catch up on new stuff in our lives, laugh at how silly everyone was in High School? My treat!" and SMILE...

ASSUME SHE WILL SAY YES...granted, she may say no, but you have nothing invested and nothing to loose...if she says no, or I don't have time next week, say bummer...maybe later and DO NOT assume it won't happen later...let it rest, be your normal friendly self...and ask her again LATER!

Wait until her break then greet her pleasantly and ask her "Would you like to....?" Name a specific thing like go to the movies or go to a club or whatever you think she would like to do. If she answers in the affirmative then set up a time "How about Friday night?" and if she is busy ask "What is a good time for you?" then "I can pick you up at your house at...".
Once the time and place are set you can make some small talk about work or about something you know she is interested in. Then say "Okay I'll see you Friday" or whenever you have decided. Always be polite but firm. Never come on too strong because that could scare her.
If she says no then thank her and you can say "I've been wanting to ask you for a while". Then "See you later". Stay on friendly terms with her.
Men have to get used to rejection because most will be rejected a lot than accepted. Don't be discouraged. Think of how many wonderful girls or women there are out there.

Enough of your what ifs?

Open your mouth and say the words.

The worst she can say is NO.

Be a gambler and take a chance.

Ask her when you two are alone. it makes a difference.

The next time you are talking to her, say something like 'there's a band playing at such and such a venue on night x would you like to go see them with me?'. Or 'would you like to catch a movie or get dinner some evening?'.

Good God, man! Never listen to my advice!
I'd just go up and ask her out.
So that'd NEVER work!