I'm not from US and I have a question : D What does "simmted" mean? Have you ever heard this word? For example - "Just simmted the test".

I think the word you are looking for is submitted. That is all I can think of. It means in the example you gave that a person has finished their test and turned it in. So it would be like if you finished a test and gave it to the teacher you would tell a friend "Hey I just submitted my test"