I have been using a VED for about
10 years - I have an Osbon Erectoaid - Classic not battery.
Normally they is an instruction manual or video with the unit -- dependent on where you get it.
Google How to Use A Vacuum Erection Device.
http://www.phoenix5.org/sexaids/veds/VED.html
There's a couple of things you may need to do.
1) Shave your pubic area around your penis - I will explain later why
2) Assemby the VED
3) Lubricate the inside of the vacuum tube 2" from the top and do similar amount on outside of tube.
4) Put the constriction ring on the tube - if you use more than one than the larger goes on first and the smaller last (first to come off tube)
5) Pump up and give the desired erection - don't pump to point it is uncomfortable.
6) When you have the erection you desire, while the vacuum is still on, slid the rings onto your penis.
as close to your pubic bone as you can get. If more than one, slid both at same time.
7) Release pressure from Vacuum tube
8) You should be ready for fun.
If you don't shave or trim your pubic hair when you remove the rings, you may also remove some of your hair. It doesn't feel good.
Good Luck and Happy Humping
Tom West Central Ohio