In one sentence, describe what the following article is about:

You'll need a venting system, but you'll have to choose between two types. There is rigid venting, which comprises a hard metal tube that works for distances no greater than 40 feet (12.2 m). There is also semi-rigid venting, which uses a flexible hose that works for no more than 20 feet (6.1 m).  In general, rigid venting is best for dryer vents that are installed at floor level. If you need to attach your dryer to a vent above floor level, you may need a semi-rigid vent hose. Or, if you use a rigid vent hose, you can attach a pair of elbow-shaped bends to the top (where the hose connects to the wall) and the bottom (where the hose connects to the dryer). Dryer vent hoses should be 4 inches (10.16 cm) in diameter. Use a metal vent hose rather than plastic or vinyl, as these are a fire hazard. Make sure the connections at both ends of the vent hose are secure. You can do this with hose clamps, duct tape, or foil tape. However, hose clamps are the most secure option, as tape can eventually dry out and lose its adhesive properties. Make sure that it is clear of lint and other blockages, and that the vent hood is still in place. Carefully clean out any buildup.

Summary:
Attach a vent hose. Secure the vent with a hose clamp. Check your outside duct opening.