There are loads of YouTube video tutorials for bits you don't remember or don't understand. However, many stocking patterns are knitted "in the round" on circular or double pointed needles - would you be OK with that?
One alternative is to sign up to Ravelry.com. This is free to do and will give you access to thousands of patterns - many of them free. You can search the pattern database for Christmas Stocking patterns and then refine your search even further by (for example) specifying
Free Knitted Thickness of yarn
You can also specify that you want a seamed pattern (this means it is worked on two needles) or you can look at the pattern description and it will tell you how it is worked.
You would get a two colour striped stocking out of 2 100g balls of yarn how much that costs is entirely personal preference. Stylecraft DK for example costs about £2 for a 100g ball and is a perfectly good, hard wearing, easy to knit with acrylic yarn. Yarns with cashmere or merino fibres cost considerably more but are fabulous to work with and would produce an heirloom piece. These tend to come in 50g balls though so you would need two of each colour.
If you go ahead and come across any problems, post here and someone will always help you out.
That one would be easy though it is probably knitted in the round. Which is also easy, it's just different. Horizontal stripes are incredibly easy.
I agree with TheWoolly - come on over to Ravelry. I just did a quick search there and found 65 free knitted flat patterns available online. Some look even easier than the one in your picture, some are harder, and there are several which are similar stripy.