Also, when I put links on my posts they did not show up for a day or so. Why might this be?
That's odd, unless they are advertising links.
Are they affiliate links?
http://en.support.wordpress.com/affiliate-links/
Or are they another type of advertising links?
http://en.support.wordpress.com/advertising/
This is guide for creating links in blog posts and pages and it does sound like you are following it.
http://en.support.wordpress.com/links/
This is the general link model:
<a href="URL HERE">Highlighted anchor text here</a>
This is the visual result but as it's just an example it's not actually linked to a page:
Highlighted anchor text here
Enter the anchor text you want to link to first.
Then use your mouse to highlight that anchor text.
Next click the chain icon in the Visual editor and proceed to create the link.
If you still have trouble with links then please post a link to a post or page with an example in it that we can examine.