The magic word is "sprintf()".
The LCD routines already have got a conversion routine for integer to numbers. To read data in HyperTerm (or PuTTY) you need to convert the data to printable ASCII characters which is done best with sprintf(). Instructions for use here.
In Project -> Build settings set Use newlib-nano and use newlib-nano float formatting to TRUE.
In .cydwr -> System make sure that heap is at least 0x0100