This Runescape construction guide is only the basics, there isn't much to this skill really, most of it is explained in-game.
First things first.
Go to Falador (On a members world) and go to the building halfway between the east bank and the furnace. This building has a house icon over it on the mini map.
Go in here and talk to the estate agent. Buy a house from him for 1000 gold. He'll also give you a book which explain pretty much everything you need to know.
Now you need normal logs. They are all over Runescape so cut them where you feel is best. Personally, for normal logs, I think South of Seers is a good easy to reach and tree filled area. Go cut as many as you like. You'll need about 160 of so to get your construction high enough to use oaks (The next level log up).
Now you have your logs, you need to make them into planks. To do this you will need a bit of cash i.e. 100 gold for every normal log you have. Now go to Varrock. Go the the lumber yard North East of Varrock. If you can't find it, then follow the path north east of varrock, when it stops, just keep going north east.
There are probably massive crowds of people so it shouldn't be easy to miss :)
Right click on the man in grey (The yellow dot on your minimap) and select buy planks. Click on normal planks, and he'll turn your logs into planks for you.
Now you need some nails. You will probably need no more than 3 inventories full of iron to convert into nails to start with. Grab some iron bars and a hammer, then smith them into nails (Go the the little hut North of Falador).
Now take all of your nails, about 50k (That's a bit overkill, but you never know :) ) and as much wood as you can carry to Rimmington. This is South West of Falador. You'll eventually come to a MASSIVE crowd of people. In the middle of this crowd, you'll find a portal. Click on it and select "go to house in build mode".
You'll go to your house in build mode, which lets you (Surprise surprise) build stuff. First of all, right click on one of the doors and select build room, now pick the parlour (As you've already got a garden). Now click on all the white furniture (Just the chairs for now and you're level isn't high enough) and click build and select from the options for what you want to build. It says what materials you'll need and the level required.
At the moment you can only build normal wooden chairs, so build them for a while to get your level up.
From there it's just wash rinse repeat for the rest of the rooms :)