Release the tensioner bolt to allow the spring to apply pressure to the belt.
If you are replacing a blown head gasket, cleanliness and exact clamping forces are paramount. The 1G-FE uses Torque-to-Yield (TTY) head bolts, meaning they stretch when tightened and every time they are removed. Cylinder Head Bolt Tightening Sequence
, but the "hot" part of your query suggests you might be seeing specific links or "hot" deals online that look a bit suspicious.