Writing the bootloader program into ATmega32A
The ATmega32A Datasheet on page 245 shows the following table of where the bootloader area starts depending on how the BOOTSZ fuses are set:



So assuming you have BOOTSZ0 and BOOTSZ1 are both cleared for the largest bootloader section it will start at 0x3800. From the memory sections documentation you can see the code goes into the .text linker segment and the address may be changed by going under Project properties | Toolchain | AVR/GNU Linker | Memory Settings and adding .text=0x3800 under the FLASH segment section:



Normally if I want the bootloader combined with the application firmware for production programming I use the bootloader to load the main firmware and then read back the result from FLASH. It should be technically possible to combine them using custom linker segments but you'd have to be very careful about where things like standard library functions were placed so the former method is probably easier and safer.