Various sections of site on menu.. how to do it?

You need to create something that will live at each of those top-level menu items -- maybe an intro page, or a view?

> I am planning to have the following sections
> I can see the final result but not a way how to do it.

The first thing you should realise is that Drupal represents a paradigm shift away from 'section-based' content. This is why you are finding it difficult to conceive of a section-orientated implementation.

> when i am trying to add these (the above) "Primary menu" items, it asks me for a URL where the Menu Link should lead

Taking them one at a time:

Home (A Blog)

For a teaser list of all user blogs the url should be: blog

For a teaser list of your blog only, the url should be: blog/N where N is your uid
You can make an alias for this so that blog/N is domain.net/myblog

If you don't like this default teaser list, you can create your own list using the views2 module.

Linux & Travel

Two main ways to usually do this:

You may wish to have two separate content-types for them. This would be handy if you wanted different fields on the create pages. Eg. the travel content-type might be more focused on images as part of the content, which you wouldn't use whilst writing Linux articles. You'd then use views2 to make a view for each content-type, at the respective urls: /travel and /linux

You could also have one content-type, and use 'taxonomy tagging to differentiate between the two. You'd tag all linux articles with 'linux' and all travel articles with 'travel'. There is a default core teaser list for this: taxonomy/term/N where N is the id of the taxonomy term. Again, you could create aliases for this, so the urls become /travel & /linux. And again, if you don't like the core teaser list, you can create your own using the views2 module.

Note you could also combine the methods and have two content-types, which are then tagged with relevant taxonomy terms. For example, what if you went to a Linux convention in Latvia? You could create the content as a blog post, then tag it with 'linux' and 'travel', and it could display in all three 'sections'.

Pictures

There are too many ways of making a gallery. This is something you should take a couple of weeks to research and experiment with. But at the end, you will have a url to link to from the menu, whichever method you use.

Contact

Site wide contact page is at url: contact
Individual contact page is at: user/N/contact where N is your user id
You need to set the contact module up in the admin backend

About (My resume)

If you use the default 'page' content-type to create your resume, you can access it at: node/N

> and inside that, expand "Menu settings" and select "Blog" (or whatever primary menu item,
> i.e. section i want to place the article into) from the drop-down.
> This would make it appear in the correct section.. no?

You could do, but that isn't how I'd do it. I'd try to keep the menus as sparse as possible, pointing to automatically generated lists of content as opposed to individual nodes (pages). It is these 'lists' that form your 'sections'. For your example above, apart from having a teaser list of blog posts, I might be also tempted to use 'block view' to list recent blog posts, or blog posts archived by month.