You need:
A pack of skins preferably red king Rizla skins for the beginner
Some tobacco
Some weed
A piece of thin cardboard
A lighter / matches
Rolling guide:
Put the skin on a hardback book or a dish in your lap within easy reach of your hands.
Pull your weed apart and spread evenly over the skin.
You can tear off a bit of the Rizla pack for a roach; roll it into a cylinder and put at the left end of skin. NB some people find it easier to roll with the sticky end facing you, some the other way, only by trial and error will you find which way suits you.
Spread tobacco over your weed in the skin again evenly throughout you can aim for a 60(tobacco)/40(weed) mix to start with.
Now pick up the skin with both hands between your thumbs and first two fingers.
Using your thumb, roll the skin between your fingers trying to make a cylinder shape with it.
The more evenly a cylinder you can get the better unless you want to try making the smoking end a bit fatter to go for a proper spliff look.
Roll more and apply pressure to the part you wish to roll first, make the edge closest to you (if the sticky edge is furthest)catch under the opposite side of the skin. This is the only tricky bit. Once you can make one side roll into the other and wrap around itself you have the knack.
When you finally get the paper to catch, wrap it around, lick the gum (the shiny sticky bit) of the paper and roll fully.
Poke the smoking end (without the roach) down a bit with a pen.
Twist of the end for a nice finish and light up.
The trick of rolling is all about getting the paper to catch and wrap itself around. Once you have learned this you’ll be flying. It is very useful to buy some rolling tobacco and to practice with little skins first. Once you have mastered rolling a spliff at all you can start adjusting the shape to make some real fat spliffs.