I want to be able to say "I will try to" for example "I will try to visit my friend again". Searching "To Try" on Denshi I got 試みる (こころみる) but I'm not sure how to add this to a sentence. I have an okay understanding of basic Japanese grammar but this type of sentence hasn't come up before ^^" Please could someone help me?
You can use the ~て form of a verb and add みる to it (for example 話してみる - try to talk). If you want to use 試みる you should use it with nouns (for example 友達を訪ねる事を試みる。 (「事」 being the noun) - I will try to visit my friend).