[pushkins]

If it's a more modern double hung window then your task is a really easy one.

Open the window a few inches then at the top of the window on either side of the lock you will see two little pieces of plastic that slide in to wards the lock. Slide both these to wards the lock (in wards) at the same time and also at the same time gently pull the entire top part of the window (bottom section) out just a little, once you are clear of the window frame you can let go of the sliding latches. You now should be able to lay the window all the way down (like your going to clean the outside). Lay the window down to about 90 degrees, once you have done that, holding the bottom section of window that is still in the window frame tracks move the right side of the window up, keep moving the window up on the angle until it disengages the window frame. once this side disengages pull the other side out.

Presto, your window should be out.

To replace the window, do exactly the reverse. Holding the window with the left side lower sit the left side into the window frame on it's guide, then move the right side of the window down to catch on the higher side window catch. Once both sides are in their respective guides move the higher side (should be the right side) of the window down until the window is again level, then simply tilt the window back up and press it back past the upper latches.