Your gear! Take the 20 or so feet of webbing and cut it in half. Once cut in half tie the ends of the individual pieces together forming two separate loops. (Disregard yellow rope).

Find two solid posts to string up the slackline. Once you find your spot grab on of the loops you made in the last step, throw it around the tree and connect with a carabiner. Lets call this C1.

Take one of your rings. Pinch the webbing and send it through the ring as shown. Lets call this R1.

Continue the pinch around and back through the ring. At this point connect to C1. This would be a good time to adjust height. Waist height is a good starting point.

Walk about 75% of the way to the other post. Stop. Repeat steps 3 and 4. Instead of connecting to a carabiner attached to the second post and connect as shown. Lets call this C2.

So repeat step 1 on the other post (C3). Take the webbing and loop it through C3 attached to the second post. Have the webbing enter from the bottom and loop back through C2 also through the bottom.

Add another carabiner (C4) on top of C3. Have the webbing go through the top of C4 and send it back to C2.

This step is tricky. Have the webbing from C4 go back through C2 from the bottom between C2 and the webbing already through the carabiner. This webbing friction is how the slackline holds tension.

Just a little closer view of C2. Double check step 7 to make sure your design matches mine.

Time to tighten. Pull the webbing in the same direction of post 2. The slackline will tighten and lock off on its own due to the webbing friction. Make sure the webbing completely overlaps at C2!!!

Once tightened to your desired tension, pinch some of the extra webbing and tie a not. Take your fifth carabiner (C5) and connect it as shown.

Connect C5 to C3 and C4. This is a fail safe so if for some reason the webbing loses friction (has never happened to me or anyone I know), you'll be safe.

Optional stuff. If alone. Disconnect C5 from C3 and C4. Connect the 6mm rope to C5 as shown.

Add carabiner 6 (C6) to C3 as well as a pulley. Have your rope go through C6.

Add the other pulley to C2 and have the rope follow.

Pull until you're happy with the desired tension.

You're good to go! But be careful...

...it takes sometime to get the hang of this. Enjoy!