How to sit properly in classical position

[Joshua^^]

hi do you have any knowledge on how to sit properly in a classical position for electric guitar? Currently, when i use a footstool(not a proper footstool however its a small chair that i use as a substitute) and i put my left leg on it like your suppose to, my hips will start to be sore after awhile. So if you have any idea what is my problem or any info on how to sit properly pls tell me