Small changes in my word-press theme

Hello people,

I am trying to get rid off some contents word-press is automaticaly putting in my web page.

I have designed my web page on word press. I am having access to the editor “Twenty Eleven: Stylesheet (style.css)”

I am done with everything but i cant remove the following contnents:

1. Each time i make new posts, the content gets automaticaly the:
Posted on “date”
Posted in Uncategorized
I dont like having these within the wording of my posts. How can remove these? They are annoying and make the post looking ugly.

2. How can i make the buttons of my menu list showing up always on bold?

3. How can i change the size of the letters on the titles of my posts?

A friend here told me to use the child theme. Anyhow, i am not able to do it, even if it’s something really simple for many of you here. I try to build up a simple looking band web-site but i m trying it make it look as good as possible.

Please let me know, in case you know how, what should i change and where, inside the code that the editor is giving me. I have already done some small changes through it, have kicked out things i didnt like (footer etc) but i cant find everything in the code….

Hope to hear back from somebody!
Regards,

Manos