Cayenne is the largest city in and capital of French Guiana.
French Guyana's main international port of entry is the Cayenne-Rochambeau Airport (CAY), with daily flights mainly to the French Caribbean and mainland France.
Note that French Guyana has some different visa policies and some nationalities (Including the Brazilian one) must have a visa prior to arrival.
Good hotels exist, but they can be relatively expensive.
There is also Ket Tai. Single room for 43EUR, double for 50 and Triple for 60. Nothing fancy but clean and a few minutes walk from place des palmistes.