Posts in 2 languages

Hi,
I am a little bit desperate and don´t know what to check anymore.
I would like to translate my posts in a second language. My blog is already in Spanish, and I would like to manually translate (not automatic translation) my posts into english, so that my english speaker friends can click somewhere and read it my blog too.
I have read several posts and blogs about WordPress pluggins to allow you to do this, but I am not sure which one is the preferred and simple one to use with Mantra. (The easiest if possible because I am quite new into WordPress and with Mantra and don´t know how to change and CSS, codings etc yet).
I would also like to translate the Page Tittles, and Category Names into English in possible.

I even downloaded some pluggins, activated them but then didn´t know how to continue so I inactivated them again.

Please help.
Thanks
Itziar