Totally new to the self service and can't find much info!

Hi Guys,
So I have decided to tackle servicing my hiace myself. I have been goggling and searching here and am finding it difficult to find clear instruction.
I want to do the oil+filter, Air filter and Fuel.

I *need* to do it as Im getting warning lights about my oil being low and well... its long over due.

I've downloaded what I think is a manual from one of the posts on here but so far I haven't found information about changing those things.

I have a 99 model.

Any guidance would be great!