Screenshot 2, if this one helps at all

Screenshot 1

Thank you SO much! But, I have another problem... If I run the program, and choose a number, it brings me to the message you get for not typing in an option. I've tried changing the options to letters, and that just did the same thing. Should I change the IFs to WHENs or is something else the problem?

Ugh... I'm confused. I run my program, and let's say I choose 4, b/c I want to run (That part doesn't matter. It happens with all choices), then I get an error message that says "Type mismatch in line 5" I've been trying to solve this for two weeks (Got the Banhammer), do you guys know what I did wrong here?

Thanks! I was lost, since I wanted to know how I can start off the coding for a vérenére cipher app, and I guess the screenshot shows that...

So... Could someone show me how to code a monoalphabetic cipher? I have no clue where to even start.

It doesn't have anything against it... I've been doing fine w/ it, it's just a quick & accessible learning resource.

Thanks, that helped me out a LOT.

Error in line 17... Help? All I know comes from Wikibooks. I honestly am missing the slightest clue.