JEDI-SDL's documentation will help a lot. Though there are a few mistakes in it. Especially when it comes to pointer references:

A simple example for the input handling chapter:

[pascal]
var
  event_: TSDL_Event;

procedure ...
begin
  ...
  ...
  while (SDL_PollEvent(^event_)) do
  begin
    ...
  end;
end;
[/pascal]

The SDL_PollEvent(^event_) is wrong, it should look like this...

[pascal]
SDL_PollEvent(@event_);
[/pascal]

That is important, especially for Lazarus.