Since the syntax to create a table partitioning is really hard to keep in mind, we'd better use GUI tools to facilitate us to create. Before doing this, I'd recommend that you should read: how to create a normal table in SQL developer first.
Here we introduce the way to create a new partitioned table by SQL developer.
Let's see the procedure.
New a Table
Right-click on "Tables", it shows a function menu.

SQL Developer - Create a New Table
We enable "Advanced" option.

SQL Developer - Create Table Builder - Click Advanced
Column Definition
Add some columns.

SQL Developer - Create Table Builder - Column
Partition Type and Key
We select "Range" as our partition type.

SQL Developer - Create Table Builder - Partition by Range
Select the partition key. Columns which contain datetime factor are good candidates to be a partition key.

SQL Developer - Create Table Builder - Select Partition Key
Add Partition
Click on + sign to add a new partition segment.

SQL Developer - Create Table Builder - Add a Partition
Historical Data (Cold Data)
We add the first partition segment with values less than TO_DATE('2000-01-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS').

SQL Developer - Create Table Builder - First Partition
New Data (Hot Data)
The rest of rows go to the second partition segment, so we choose MAXVALUE to accommodate all new data.

SQL Developer - Create Table Builder - MAXVALUE Partition
Preview DDL
We review DDL for making sure that everything is ready.

SQL Developer - Create Table Builder - DDL
The literal DDL is as below.
CREATE TABLE SALES
(
PROD_ID NUMBER NOT NULL,
CUST_ID NUMBER NOT NULL,
TIME_ID DATE NOT NULL,
CHANNEL_ID NUMBER NOT NULL,
PROMO_ID NUMBER NOT NULL,
QUANTITY_SOLD NUMBER(10,2) NOT NULL,
AMOUNT_SOLD NUMBER(10,2) NOT NULL
)
PARTITION BY RANGE (TIME_ID)
(
PARTITION SALES_2000 VALUES LESS THAN (TO_DATE(' 2000-01-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS')),
PARTITION SALES_CURRENT VALUES LESS THAN (MAXVALUE)
);
Then click OK to confirm.
Table Created
After we have created the new partitioned table, we can try to load some data.
SQL> insert into hr.sales select * from sh.sales;
918843 rows created.
SQL> commit;
Commit complete.
We made it.