Installing windows can be two totally different tasks in this day and age, but not too long ago it only meant one thing. You're reading this because you may want to know how to install Windows software that's used on personal computers, but then again you may want to pick my brain about installing a window or two in your home. Believe it or not, I can clearly remember back when there were no personal computers and no Windows software of any type. Before Windows software was even a glimmer in his eye, Bill Gates and I were riding bicycles, throwing water balloons and throwing mud balls as we're close to the same age.

You can have problems installing new windows if you're a rookie. For starters, glass is heavy. It's shockingly heavy. Large windows can easily weigh hundreds of pounds. If you don't have enough help on hand, you can drop a window causing severe damage to the unit and/or yourself. Don't underestimate the physical effort you have to invest just to lift a window, position it and hold it in place as you try to get it into the rough wall opening. Don't forget about the wind. A gust of wind can blow the window out of the opening sending it crashing to the ground in an instant.

After installing windows in your home, you can have serious water and air-infiltration issues if you don't follow some critical steps as you're putting in the window. Fortunately, the major window manufacturers have created fantastic written instructions showing you and your builder how to avoid the most common problems installing windows. If you have a little patience and some moderate construction skills, you can do a great job of installing new windows or replacement windows.

Perhaps the three biggest mistakes I've seen people make while installing windows are:

• Missing or inadequate flashings
• Too few fasteners and shims 
• Out of square and level

Water infiltration is a major issue with homeowners. I get complaints each week about water that leaks in and around windows. Flashings are transition materials that capture water and redirect it safely back outdoors. Newer flashings are modified asphalts and other rubberized materials that come in rolls that resemble adhesive tape. When applied in a certain fashion, water simply can't get indoors.

When you're installing glass windows, you must pay attention to the instructions about the type and length of fasteners, and where along the window frame they should be placed. Don't be surprised to see a nailing schedule that calls for a nail every 12-inches. You must use shims to ensure the window frame remains straight so the window is always in firm contact with the jamb. This prevents air infiltration.

Installing replacement windows is harder than installing windows in a new house. When you're working on an existing home, you have to remove the old window and deal with an opening that could be out of square. You also have to deal with the existing interior and exterior finishes. Sometimes this can be very challenging.

Be careful if the house was built prior to 1967. The paint used on and around the existing windows you're removing could contain lead paint. You have to be really careful about the lead dust and lead-paint chips.

If you're wondering about how to install replacement windows, start by talking with the new-window manufacturer or a distributor. Be sure the windows you're buying are really meant to be replacement windows. Some windows come with integral nailing fins that surround the frame. These don't work well in a replacement window situation as the edge of the frame needs to be in close contact with the existing exterior surfaces.

You'll discover that installing house windows can be rewarding and enormously frustrating at the same time. The best way to achieve success is to start with just one small window. A small window is easy to handle. The most important thing you can do is read the written instructions until you completely understand them. Don't skip any steps.

Take your time when installing the flashings. Be sure to look at the gaps between the window and the frame at all stages to ensure the window is square in the frame. Before you drive the fasteners completely into the frame, check to make sure the window operates smoothly and it locks easily.