Can you give source code to simple encryption and decryption?

[learningtocode14]

hello i know how it works.What i use is virtual key so when someone types "a" it turns into "t" in my txt doc but when i use it,it lookes weird.Can i have some source code?

[ciphermagi]

Can I have some attempts at solving your problem yourself, so that I can build off of what you've already tried?

[Catfish]

Here you go. Have fun.
http://www.schneier.com/book-applied-source.html