I'm trying to say "I bought a web camera for skype" but how would you say the "for" bit?
Web camera for skype.
I eat apples for breakfast.
Chocolate for me.
Thank you for any help you give :)
Many Japanese learners would use "ために" frequently and it is sometimes too much in Japanese.
To mention usage, you can always use 用 as Anirudh san already mentioned.
In this case, カメラ is not for taking pictures but web camera, you can use "スカイプ用のカメラを買う".
For other two examples, you do not really have to translate this "for" in Japanese.
You should have written complete sentences, you can write for example "Is this chocolate for me?" このチョコを私に？
The situation you should use "ために" is to make an effort to do something or to do anything in place of the person.
It depends on the sentence. Japanese is not like English where you can use "for" in the same way.
この教科書は子供に対して作ったの。This textbook was made for children
この教科書は子供のために作ったの。This textbook was made for children
These two sentences means the same but of course with a slightly different connotation. But ultimately they will be interpreted the same.
There are multiple ways.
One other way is ”ように”, where the kanji is ”用”
fore example: Watashi You Ni - will mean "for me"
スカイプ用にカメラ。 "Camera for Skype"
Also: Watashi NO you ni, would mean "Like Me" , a small addition of "no"/の completely changes the meaning of the sentence.