Engine / cooling fluid problem need help asap...

[totta Crolla]

Should be relatively easy to fix.
Drain the cooling system.
Remove the blue water pipe from the outlet.
Undo the two bolts holding the outlet on, sometimes the bolts corrode inside the outlet pipe holes and will snap if too much force is applied.
You might want to get some easing oil under the bolt heads and gently heat the outlet where the bolts go through if you think they are corroded.

Once the outlet is undone and the two bolts are out the thing should just pull off of the steel pipe. There will be an 'O' ring at either end of the steel pipe, replace both. Lightly grease both 'O' rings before re-fitting. Also give both housings a good clean where the 'O' rings go in.
Push the steel tube halfway in each end and 'wiggle' the outlet into position while gently pushing the steel tube into both ends. Check both 'O' rings are correctly seated and not protruding.

You can get the 'O' rings and gasket from Toyota

Fit a new gasket to the outlet to head, copperslip the two bolts before fitting them :wink:

Re-fill and bleed coolant system.

Hope that all made sense