PS: it would be 

estoy enfermo - I'm sick 

ten go calor - I'm hot 

Hey mark, 

yes, this is correct. In Spanish, "to be" is translated as "estar" and "ser" 

in a nutshell, ESTAR is used with location, and temporary characteristics. Ex: estoy aqui (I'm here, but later I might not) 

SER is used with permanent characteristics, professions, physical characteristics. Ex: soy una mujer, soy rubia (I'm a woman, I'm blond)

in the third expression, you can see the idiomatic use of TENER (to have) to mean "I am". This is how we say it in Spanish. Other examples would be: tengo hambre/sed/miedo (I'm hungry, thirsty or scared).

hope that helps. :) 

For english is easy because you always use this rule: pronoun personnel + to be = subject+ verb
I + am
you + are
he + is
etc.
I mean the pronoun + verb "to be", but in spanish meanings for the verb to be (am,is,are): ser, estar and tener.

Maybe you can check the following page:
http://studyspanish.com/lessons/serest1.htm

Thank you, guys <3