A blog within a blog

I want to create an area of my blog for reviews/giveaways so when someone clicks on the link from my current main page post - it will take them to another area (with different header and sidebar content.-and the look of a different blog) but it will actually still be my blog.

Example: mydomain.com ( main page) but link takes them to mydomain/giveaways.

Is this a sub domain? I’ve seen these before on other blogs but don’t know how to set one up for mine.

It is possible with a subdomain. You will need to setup the subdomain in the panel (same as a domain) and install a new fresh version of WordPress.
Keep in mind that a subdomain is giveaways.mydomain.com

so basically I’m starting a brand new blog with a brand new URL and just doing a 301 direct? Is that correct?

No. You would not do a 301 redirect. That is only done if you have siteA.com and you no longer plan to use that domain and want traffic to be forwarded to siteB.com instead (or if you want the traffic to go to sub.siteA.com same thing). You want to have your main site be one thing but another section associated with your site. Simply set up a sub-domain (wordpress can do multisite too I believe which lets you keep all of the core files in one location…) and just link to it from your main site (and leave links on the sub-domain back to the main domain so people can easily get back to it).

You can also do this by adding page templates to your current theme. Your theme folder probably has a page.php file, which is the framework for your current blog. If you’re good with theme creation, you can create a “giveaway.php” template, so when you create the new page, it’ll look different from the rest of your blog. If not, then go with the subdomain idea, but it will be a completely different blog installation.

Thanks - unfortunately I’m not good with any of this. It scares me.
I just need to hire someone I guess.

If I go the sub domain route - will I have to buy thesis again, to use it for the sub domain? ( I use thesis on my main blog)

No, you simply need to copy the theme over to the sub-domain in the appropriate directory.

You can use any theme you want in the subdomain. Don’t know why you would want to buy any them, since there are 100’s of excellent themes out there which are for free and very easy adjusted to your own needs.