Help on Twitter?!?!??!?

[Will Thompson]

if I tweeted something and tagged someone in it will they see that I tweeted about them and how will I know if they reply?

[?]

yes they will see it.
and if they reply you can either see it in your timeline, and it should stand out by being blue because it mentions you.
you can also click on the button that says '@Mentions' at the top of you timeline. it will then show you all the tweets mentioning you.
you should also get an email, saying "so and so has mentioned you on twitter' so that you know!

hope i helped )