I’m assuming you are using the visual editor. If so, here it is in a nutshell:
1. Type whatever text you want to appear on your page.
2. Select that text.
3. Click on the “Create Link” button in the MCE editor toolbar. (There are two: one looks like three links of a chain, and the other one looks like three links of a chain with the middle one broken. You want the unbroken one.)
4. A link box will pop up. In the “URL” box, enter the address of your link. Be sure to include the “http://” part, which is entered automatically for you.
5. In the “title” box, type whatever text you would like to appear when someone hovers their mouse over the link. You can leave this blank.
6. Tick the box marked “Open link in a new window/tab” if you would like.
7. Click the “Add Link” icon at the bottom.
Cheers,
Ken