Congratulations on entering the world of cooking!

The easiest way is to get an instant read theremometer and use the following guidelines:

For Beef and Pork:
Rare 120°-125°F
Medium Rare 130°-135°F
Medium 140°-145°F
Medium Well 150°-155°F
Well Done 160°F and above

For Lamb:
Lamb Rare 135°F
Medium Rare 140°-150°F
Medium 160°F
Well Done 165°F and above

It's always better to take meat from the heat when it is 5-10 degrees below the desired temperature and letting it rest. 5-10 minutes for steaks and chops and 20-30 minutes for large roasts.

Never cut a roast without letting it rest. The juice inside the meat is still active and it will pour out of the meat if sliced, leaving the meat dry and grey looking.

Most health advisories state that chicken and ground meat be cooked to an internal temperature of 180°F.

Here's a linkto a previous discussion to cooking chicken breasts.

Karen