There are a bunch of extensions available to display social media feeds on your Joomla site at the Joomla Extensions Directory (JED). Most of these will take information you provide about your Facebook, Twitter, LinkedIn, or other accounts, and then display them on your web page.
Just because you can, doesn’t mean you should! If you are not updating your Facebook or Twitter feeds on a daily basis, I’d recommend you not post the feed itself on your web page. Your updates won’t be that frequent, so it will look like you’re not that interested in what you’re doing. (And yes, I realize the real reason is that you’re just way too busy to post!)
If you have Facebook and Twitter accounts, but you don’t post that often, you could always post a link from your Joomla site to those pages. In that way, you don’t have a feed on your site, but you do have a link where people can go to see what you’re doing.
Download the right icons for the social media, resize them if required, and include them in an article or a custom HTML module as you would with any other type of image. Link the images to your Twitter and Facebook pages from there.