Are you talking about the cheap cloth covered type with tent poles and strings, or a heavy duty pergola?
If it is the cloth covered type, assemble the roof tent poles, stretch the cloth over the roof frame and then raise it up and install the tent pole legs under it. Then stretch the strings that hold it up and stake them tot he ground.
The heavy duty type of Gazebo requires some more info. Who made it, and what model number is it? All of them are different.

Related posts:

1. Where Can I Buy Replacement Hexagonal Gazebo Joints From Plz? Look at the following sites. Gazebos & Arches At Haggul...
2. Sunjoy Gazebo – Sun Replacement Canopy This canopy fits gazebos that were sold at Target for...
3. Where Can I Buy Mesh To Attach To A Gazebo To Hang Art On? Im looking for Mesh that I can buy to hang...
4. I Have 12×12 Gazebo Purchased From Home Depot.was Woundering If I Can Use Wood Post Instead Of Poles In Box.? Bought gazebo for back yard.Would rather use wood post instead...
5. How To Set Up My Greatland Outdoors Gazebo- Instructions Are Missing? I got it at a yard sale and there weren’t...

• Gazebo Parts Replacements?
• How To Choose a Garden Gazebo
• Arrow Gazebo (Home Depot) Replacement Canopy Cover
• Where Can I Buy Mesh To Attach To A Gazebo To Hang Art On?
• Sunjoy Gazebo – Sun Replacement Canopy