How to concatenate fields in zpl, and how to use conditional statement?

This is my zpl code:

^XA
^MCY^PRD,D,D^MMT,N^XZ
^XA   
^FWB                                                                                        
^DFCASENEW^FS                                               
^LH0,0                                                    
^FO15,90^A0,90,88^FN01^FS^FX Company^FS
^FO1650,430^A0,163,114^FN02^FS^FX Item Number^FS 
^FO250,59^A0N,109,78^FN03^FS^FX Description^FS 
^FO250,150^A0N,90,58^FN04^FS^FX Units Per Carton^FS 
^FO320,150^A0,90,108^FDX^FS  
^FO380,150^A0N,90,58^FN05^FS^FX Net Weight^FS
^FO450,350^A0N,90,58^FN06^FS^FX CaseUPC^FS 
^BY3.4,,230^FO130,450^BCN,,N,N,N,N^FN07^FS^FX RotationProduct^FS
^FO10,703^A0N,32,94^FN08^FS^FX RotationProduct^FS
^FO150,63^A0,100,102^FN09^FS^FX Rotation^FS
^FO1562,50^A0,90,66^FDBest Before^FS     
^FO1650,30^A0,134,100^FN10^FS^FX BestBefore^FS    
^XZ                                                           

^XA^XFCASENEW             
^FN01^FDLawn Mover^FS                        
^FN02^FD1234^FS                           
^FN03^FDVeryTastyProduct^FS  
^FN04^FD10^FS  
^FN05^FD150 G^FS  
^FN06^FD000234523447990^FS                           
^FN07^FD(01)00077123456789(19)12345(10)A1230(21)4588^FS                              
^FN08^FD(01)00077123456789(19)12345(10)A1230(21)4588^FS                                    
^FN09^FDA1230^FS                          
^FN10^FD01JUN17^FS                        
^PQ1,0,1,Y                                
^XZ                                       
^XA^MCY^XZ

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So i am relatively new to zebra programming language.

i need  for the company do a if then on the zpl,
for eaxmple

if company #12345
Then Company1
if  company #67891
Then Comapny2

Also how can i add similar fields together? for example

i want CaseUPC + RotationProduct + Rotation as one field

^FN06^FD000234523447990^FS  + ^FN08^FD(01)00077123456789(19)12345(10)A1230(21)4588^FS +                                  ^FN09^FDA1230^FS

one last question,

is there a way for me to do a substring on these fields, i have a field : ^FN06^FD000234523447990^FS i need the starting 0 to be one font and the following 5 numbers to be another font, i then want another 9 to be another font.

i am new to ZPL programming i looked at https://www.zebra.com/content/dam/zebra/manuals/en-us/software/zpl-zbi2-pm-en.pdf for help but i am not understanding how i can do  

10 IF A$="0" THEN
20 PRINT "ZBI IS FUN"
30 ELSE IF A$="1" THEN
40 PRINT "ZBI IS EASY"
50 ELSE IF TIME=1 THEN
60 PRINT "It is one second past midnight"
70 ELSE
80 PRINT "X=0"
90 END IF

in my case :(