Reddit mentions of Marx's Kapital for Beginners

In addition to seconding Qwill2's suggestion of the Harvey lectures, I'd also suggest reading Marx's Preface to the Critique of Political Economy it's incredibly short and is a good very first introduction to Marx, I think.

As a really simple introduction, you should look into getting Marx's Kapital for Beginners. It's made in the same style as "Marx For Beginners" by Rius which is linked to in this subreddit's sidebar. It's basically like a comic book documentary. It might seem silly but it's actually a very effective way of communicating the basics and I think serves as a great introduction. It's also pretty cheap to get used.

If you're looking for more substantial books to help you read it, I'd actually suggest David Harvey's Companion to Marx's Capital which has a lot of the same content as his lectures, but some additional info and has the added bonus of being text that you can make notes on, refer back to etc. I used it and found it very helpful.

I'd also suggest checking out Brenden McCooney's Law of Value Series as well as all his other videos which do a great job of presenting not only Marx's ideas but some ideas of later Marxists in a very accessible way.

Also, Ernest Mandel's Introduction to Marxist Economic theory is a popular resource. You can read reviews of that here.

Edit: I agree with Ksan's advice too.