The thanksgiving offering was made of two measures called "ephah," which equaled twenty "tenths" or "issaron," or approximately 100 pounds of flour. In the desert, they used a measure called "se'ah," and this amounted to six se'ah. When they came to Jerusalem, they increased all measures by 20%, so in new measures this was not six but five se'ah.
The leavened loaves were three time larger than the unleavened ones. The latter were of three types: oven-baked loaves, wafers, and loaves first scalded in water, then baked, and finally fried in oil.
From each of the four types of bread, the kohen would take one whole bread as his portion, and the remainder was eaten by the owner. To eat it before the next morning, the owner had to invite many guests, and he would explain to all what his thanksgiving was for.
Art: Jacobus Vrel - Street Scene With Bakery