On an English keyboard:
For an acute accent, enter Ctrl+' (apostrophe) followed by the letter - for
example Ctrl+' followed by e gives é.
For a grave accent, enter Ctrl+` (acute accent) followed by the letter - for
example Ctrl+` followed by a gives à .
For a circumflex, enter Ctrl+^ (caret) followed by the letter - for example
Ctrl+^ followed by e gives ê.
For a cedilla, enter Ctrl+, (comma) followed by the letter - for example
Ctrl+, followed by gives ç.