To sign the word “have” appropriately depends on its meaning. 

Have (things)
Have (acted)
have no
Have not 
Have to
Have been

Examples
have (things)
I have a box. 

have (acted)
I have seen you before. 

have no
I have no food. ​

have not
We have not met. 

have to
They have to work. 

have been
I have been reading.