How to use ranges?

[Doolan via Digitalmars-d-learn]

I keep running into areas of my code where it looks like I'd 
benefit from using ranges, and then I try to do some range stuff 
and my compiler tells me I'm using the wrong types, or there's 
this problem, or that problem... so I'm scared off and I just 
figure ways to work around using ranges.

I've tried reading the documentation, but for a language priding 
itself on being readable and nice to look at, it really should 
have less complicated docs:

auto tee(Flag!"pipeOnPop" pipeOnPop = Yes.pipeOnPop, R1, R2)(R1 
inputRange, R2 outputRange) if (isInputRange!R1 && 
isOutputRange!(R2, ElementType!R1));
auto tee(alias fun, Flag!"pipeOnPop" pipeOnPop = Yes.pipeOnPop, 
R1)(R1 inputRange) if (is(typeof(fun) == void) || 
isSomeFunction!fun);

(That's fine as secondary information, but this is the heading 
for this function...)

And the use of auto everywhere makes it really hard to tell what 
types I should be using for anything. My compiler talks about 
RangeT!(whatever) but you try to use RangeT!(whatever) and you 
find out RangeT is private...

I don't mean to complain so hard, I obviously like D enough to 
want to use it, just the current amount/layout of documentation 
can be frustrating at times.

Can someone give me a short summary of how to use ranges? And how 
do they relate to slices? That line is really blurry...