Get process memory image

My goal is to create a method that takes a process descriptor and returns an array of bytes representing this process memory. Here is what I have:

    [DllImport("Kernel32.dll")]
    public static extern bool ReadProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] lpBuffer, UInt32 nSize, ref UInt32 lpNumberOfBytesRead);

    public static byte[] MemRead(IntPtr handle, IntPtr address, UInt32 size, ref UInt32 bytes)
    {
        byte[] buffer = new byte[size];
        ReadProcessMemory(handle, address, buffer, size, ref bytes);
        return buffer;
    }

I do not know what to pass to the method wrappers as arguments. I can find handle, and bytesis the output variable, but what about addressand size? Where can I get this data?