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Open your package of Command hooks, and find the adhesive strip. Find the side that is red, then peel that liner off. Once you have the liner off, press it against the back of the hook.  If the liner is not color-coded, look for the word "hook" and peel that side off instead. Some adhesive strips have little pull tabs that are used for removing the adhesive from the wall. Make sure that this tab is sticking out of the bottom of the hook. If your hook's liner was not color-coded, look for the side that is labeled "wall." Peel the liner off, and press the hook against the wall, right between your pencil marks. Hold the hook firmly against the wall for 30 seconds. Make sure that the hook is oriented correctly. The hooked part should be pointing down, with the tip curving upwards. Some types of Command hooks slide out of the base that you attached the adhesive strip to. Slide the hook upwards to reveal the rectangular base. Press the base firmly against the wall for 30 seconds, then slide the hook base into place. Skip this step if you are using a simple hook that does not slide off of the base. You will need another hook on the other side of the window. If you are using a large and/or heavy curtain rod, install a third hook in the middle, between the 2 outer hooks. Do not jump ahead and hang the curtain rod up just yet. During this time, the adhesive will bind to the wall. Don't get impatient and hang the curtain rod before the hour is up, or the hooks will fall off. You can now hang your curtain onto the rod. How you do this depends on the type of curtain you are using. For example, some curtains slide directly onto the rod, while others must be secured with curtain rings or tabs.
Remove the red liner and press it against the back of the hook. Remove the black liner and press it against the wall for 30 seconds. Slide the hook off of the base, and press the base against the wall, if applicable. Repeat the process for the other hooks. Give the hooks 1 hour to bond to the wall. Place the curtain rod onto the hooks.