Can I play if I have no clue how to?
Diplomacy is really easy. For each turn, you'll try to move each Army or Fleet you control from one zone to another or declare that it will hold. Armies and Fleets can also support moves or holds by other Armies and Fleets if they could make the move themselves. The unit with the most support gets to occupy the zone, with a holding unit winning ties; a displaced holding unit moves to an empty adjacent zone or is disbanded. The only other order is that Fleets can convoy Armies across sea zones.
Orders are phrased by A or F for the unit type, the name of the zone it's in and either the name of the destination if it's moving or the order it's supporting. So to move a Fleet from London to the English Channel you'd write:
F London - English Channel
If on the next turn the Fleet wanted to convoy an Army from London to Calais, you would write:
A London - Calais
F CON (A London - Calais)
And if you had a unit in Paris wanting to support the move, you'd add
A SUP (A London - Calais)
The next turn you want to keep Paris but are worried you might get pushed out, so you order:
A Paris HOLD
A Calais SUP (A Paris HOLD)
After every other turn you count the number of supply centres occupied by each player, and they adjust the number of units they have to match that number with build and remove orders.