To add more keywords to your existing AdWords account, you'll want to complete the steps outlined below.
- Sign in to your AdWords account at https://adwords.google.com.
- Click the Keywords tab.
- Click the +Add keywords button at the top of your keywords table.
- Select which ad group you'd like to add your keyword to.
- Add your keywords to the keyword box, one per line (your keywords can include multiple words).
- Click Save.
Here you can find more information about adding or deleting keywords. I hope this helps.