How do you put it all together?

I'm able to swim about a mile.
I'm able to bike 27.5 miles.
I'm able to run 4.5 miles.

How do you put all these things together? I've done shorter distances where I would swim then run or bike then run. Today I tried to bike the full distance then run the full distance.

The weather was beautiful but a little windy. I couldn't run for more than a mile before my quadriceps started to "lock up". I would stop and stretch them out but I ended up running less than 2 miles on a 3.5 mile course. I gotta get it together for this event. I only have 5 more weeks!