You can easily add Paypal button for payment in your web page by this guide.
Generating Buy Now button
1. Go to paypal website to generate button at https://www.paypal.com/buttons/ , select Buy Now.
2. Insert information for your item, and click Create Button.
3. Paypal will generate html code which is promptly to use, click Select Code to copy it.
Inserting to your web page
1. At Content editor, select position you want to insert Buy Now button. Click HTML Editor.
2. Insert html code you got from paypal, and click OK.
3. Click Save and My Site to publish it to your website.
4. Here you go!