There are several BTC exchanges to pic and choose from....just read the reviews of the ones that are appealing. From there, you should be able to make sound decisions for buying from that exchange. Its perfectly legal to buy BTC. Also, dont forget to use a VPN when using your BTC and making purchases, especially if the website you are buying from will allow you to use one. Some exchanges wont let you use a VPN when buying/selling.

Keep in mind - every Bitcoin transaction is permanently public for the whole world to see, but it might be hard - or easy - to know who owns a particular address.

If you care about anonymity, also consider using a mixer. The "complete guide" does not mention that.

I had my post moderated last time I named names, but you can search the web:

"bitcoins for cash"
"bitcoin mixer"

First results for each are good to check out. When you trade the cash for BTC, the BTC will end up in an address. If you have reason to care, think a bit about how an interested party might link that address back to you.

Do a search above and you will see "bitcoin your complete guide" go to the magnifying glass and put in bitcoin and the guide will be your first choice