How to set up relations

I'm new to databases. Using SQLite3 to store Objects of a Lua script, I want to interlace 2 tables.

Let's say the lua objects look like this:

class_A.name           = ""
class_A.currency       = 0
class_A.salary         = 0
class_A.misc           = {}
class_A.customers      = {}  -- this stores related objects of class_B
class_A:function1() something is something end
class_A:function2() something is something else end

class_B.name           = ""
class_B.id             = ""
class_B.value          = 0
class_B.consultant     = {} -- this stores related objects of class_B
class_B:function1() something is different end

Now I'm storing these in SQLite tables. The "relatedObjects"-var should be stored in a 3. table, this should look similar to this:

-- class_A table:
| Idx  | Name  | currency | salary | misc |
|------|-------|----------|--------|------|
|  1   | john  | 1,233.00 | 2,300  | null |
|  2   | eva   | 4,100.00 | 1,970  | null |

-- class_B table
| Idx  | Name     | currency | salary | misc |
|------|----------|----------|--------|------|
|  1   | peterson | 1,233.00 | 2,300  | null |
|  2   | griffin  | 4,100.00 | 1,970  | null | 
|  3   | simpson  | 2,738.00 | 2,100  | null |

--Interleave
--index of the respective table
| consultant | csutomer |
|------------|----------|
|      1     |    2     |
|      2     |    1     |
|      3     |    1     |
|      3     |    2     |

I hope you got my point, don't think this is verry difficult and thus I feel pretty dump right now. The Idx value is AUTOINCREMENT, so ther should not occur any confusion.

The question is HOW TO set up this Interleave table.