Lots of smoke coming out bonnet after putting.

Which gasket did you replace? The intake manifold gasket or the exhaust manifold gasket?

Check for exhaust leaks. If you replaced the exhaust manifold gasket, did you use a lot of penetrating oil on the bolts to free them?

If it was the intake manifold gasket, check for coolant leaks - burning coolant creates a lot of smoke. Recheck everything for leaks.